Accession Number:

ADA209249

Title:

Apparent Infrared Radiance of the Sea

Descriptive Note:

Interim technical rept. Sep-Nov 1988

Corporate Author:

NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA

Personal Author(s):

Report Date:

1989-02-01

Pagination or Media Count:

20.0

Abstract:

Near-surface measurements of infrared 8 to 12 microns horizon radiances are presented for 2 days with differing surface wind speed conditions and vertical profiles of meteorological parameters. A representative aerosol size distribution model for each day was chosen which allowed calculations to best match the measured horizon pixel radiance and the atmospheric optical depths determined from the upwelling solar radiances detected by Channel 1 0.58 to 0.65 microns of the Advanced Very High Resolution Radiometer AVHRR on board the NOAA-9 satellite. The selected models were then used to calculate the apparent sea surface radiance as a function of zenith angle using a modified version of LOWTRAN 6. This program incorporates a statistical wave slope model to account for the contributions to the apparent sea radiance from sky reflections and emissions from the surface wave facets and atmospheric path. Good agreement between calculated sea radiances and those measured at an altitude of 33 m was obtained within 1 deg of the horizon for low and moderate surface wind speeds. Using these models, the relative contributions of the three components to radiances received at different altitudes from other zenith angles were determined. The calculations showed the emission of the intervening atmosphere to be the major contributor to the apparent sea radiance received at higher elevations from zenith angles within a few degrees of the horizon. The resulting variations of apparent temperature of the sea surface with zenith angle were also found to be strongly dependent on the vertical profiles of air temperature. FLIR, Marine atmospheres.

Subject Categories:

  • Meteorology
  • Physical and Dynamic Oceanography
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE